


It Was Just Once, Blue

by KongStudioz



Category: Underfell - Fandom, Undertail - Fandom, Undertale (Video Game), underswap
Genre: But Red turns good afterwards, Forced, Forced Sex, M/M, Poor Blue, Rape, SansXSans, Sanscest - Freeform, Shitty Writing, Slow Updates, ufsansxussans, why did i do this
Language: English
Status: In-Progress
Published: 2017-01-27
Updated: 2017-02-12
Packaged: 2018-09-20 05:02:11
Rating: Mature
Warnings: Graphic Depictions Of Violence, Rape/Non-Con, Underage
Chapters: 2
Words: 2,861
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9476801
Author URL: https://archiveofourown.org/users/KongStudioz/pseuds/KongStudioz
Summary: Upon entering a new domain, without him even knowing at first, he slowly begins to fall in love with one of the millions of counterparts of his, which happens to be Blue. Fell doesn't know how to go back to his own timeline, but he'd much rather stay here than go back to that hell hole and his brother, the Devil himself. But will Boss even care about looking for Sans in such a place that even he hated at first?





	1. Chapter 1

**Author's Note:**

> My original work is on Wattpad, but I wanted to put it here because... Just because *U* Anyway, please enjoy my shitty work-

" _Fuck_ -!"

Fell face-plants against the harsh snow and immediately pushes himself to his feet. He didn't want Boss to punish him again if he found Fell laying down like this, even though it was not his fault as usual.. He dusts himself off of any snow. "He's gonna _kill_ me." The skeleton mutters bitterly and frowns. "Why's my magic all crazy 'n shit-" Fell asks nobody and tilts his head in confusion as he makes his way back home, not really using his teleportation this time due to the way it has been acting up these past few days.

Boss was porbably expecting him to be early for his 'training' again, and hell, Sans should _never_ be late for that. The snow underneath him crunches and he kicks at it in a bit of fury. Why was Papyrus like this? He treats Sans like shit and expects him to be fully functional the next day? **_Fucker_** , he mentally insults his brother, fearing that he might be around and able to hear him. He quickens his pace though, and after what felt like hours of walking, he finally reaches the sign that read ' **Welcome** **to** **Snowdin** '. But he halts when he sees it.

That's not right.

Fell walks closer to it. "What the fuck??" It wasn't bloodstained, nor did specks of dust decorate the surface of the snow around it. Or anywhere, for that matter. With a huff, he continues his route and eventually reaches... home? **_Why does it look like that? What the fuck are those dumb lights doing there?_**

**_I_ _s this even my house_ -**

He panics a bit on the inside, but quickly steps in, for Boss didn't like waiting. "B-Boss? I'm here?" He's usually sitting at the sofa, but there was no sign of him. Sans worries and looks around the eerily similar house, finding nobody.

And just as he was about to leave, a door slams open, making Fell flinch terribly.

"Bo-"

He stops halfway as soon as he lays eyes on another monster. He looked very similar to Fell, but he wore useless armor instead of his mustard-smelling jacket, the much smaller one had a tattered, blue scarf instead of his own collar, and his set of piercing red eyes were replaced by a pair of starry-eyed, baby blue ones. Fell's heard of timelines, but has never come across _this_ particular one. He connected two and two and understood why the Underground looked so different. He must've traveled to another timeline, which was quite rare to say the least. 

Especially during his attempted teleportation.

But even if this was Fell from another timeline, he looked rather _pathetic_ with that costume on.

The smaller skeleton tilts his head in utter confusion, making Fell sneer. "What are you doing in my house? Are you lost? Are you one of Papy's friends? I've never seen another skeleton in Snowdin before! Are you visiting from Waterfall? Or perhaps Hotlands?" Fell glares down at his double, making him shrink a little. Not even three minutes in and this fucker was pissing him off..

"Came from Waterfall." He lies, smiling down at him in a sickly sweet way. "O-Oh! I've never seen you when I go visit Alph-"

"Mm-hm." He cuts him off, roughly grabbing him by the scarf and tossing him to the ground behind him. That causes Blue to bash his skull on the floor, and he cries out in pain as he tries his best to scramble up, but Fell is quick to press down on his smaller chest with a heavy foot.

"Hehe.. Where ya going, kid? You have nowhere to go now, so _stay_ _still_ and this won't hurt as much, because I want to have a bit of _fun_ ~." Fell chuckles rather darkly and leans down a bit. His counterpart whines and desperately tries to push the great force off of him as he felt his ribcage nearly crack under the pressure, and luckily enough, Fell steps off. "Yer fuckin' pathetic, ya know? Just look at yourself. Ya look so dumb with that thing on." With a swift motion, Blue's scarf is removed and dangling in front of him in a matter of seconds. "N-No! Stop! Don't touch it!" He whimpers and quakes where he lays, tears immediately pricking at his eyes.

"Haha! Are you really cryin' right now? I haven't even done anythin'. How fuckin' stupid!" A deep cackle emits from him, and without further ado, he grips the fabric in both hands and begins to rip it apart, the tearing sounds forcing the Sans on the ground to start kicking at him. But with some practiced magic, he pins Blue's arms securely above his head and leaves only his legs to flail at him, never landing a single kick on Fell.

He laughs some more as he pulls the precious memory apart, finally snapping it in half. The edgy double discards of the remains and straddles Blueberry's hips in a hurried manner. "Wh-What are you doing?! Let go of me! P-Please!" His protests and whines for release are ignored as Fell's hands roam about the fragile figure below him, slowly removing his useless armor. "Don't worry, kid. You'll like it if ya don't fight it-"

"I said. Let. Me. Go!" Blue yells, and that earns him a harsh slap to the face.

"Shut the _fuck_ up, you little _shit_!" Fell snarls, his right eye glowing dangerously in fury. Blue quiets instantly, though gasps and heavy breaths continue to emit from him.

"That's more like it." Fell comments sweetly and lowers his head, breath tickling at Blue's neck as he turns away from him. He snarls, impatiently reaching for his shorts and pulling them down, a rather dark blush forming on Blue's face. "S-Stop..Please- Please don't.." More tears stream down his face, but the edgy Sans laughs at that.

"Just stay still."


	2. Chapter 2

**Summary for the Chapter:**

> Red and Blue do the frickle frackle, and paprika never comes home

**Notes for the Chapter:**

> Again, i'll be having slow slow updates :/ I just really need to keep more focus on my schoolwork. But, spring break is here, so maybe i'll be able to update two-three chapters during this week :) Anyway, enjoy my poorly written smut :^)

Sans knew about these type of things, yes. Due to the fact that  _Papyrus_ wouldn't clear his search history. He happened to find a certain website open amongst his older brother's phone whilst he was showering in the other room.

But was when he was just a baby bones, so it didn't really affect him then. Is..

Is this what was going to happen to him?

Will his strange, rough duplicate force him to do things that go against his will..?

Papyrus... He will surely help him! He'll be home in no time!

Right..?..

He eyes his darker version, constantly looking down at the red, glowing bulge tenting in his pants. Blue swallows a heavy lump in his non existing throat and looks away, but is roughly grabbed by the chin and forced to look back at this Sans.

"Don't ya dare look away, scrub. I wanna see the look on yer face when I put it in." That made Blue gasp and kick his legs again, but Fell was quick to push them down. He whimpers, a noise he absolutely _hated._ It made him feel weak and lesser than anyone who heard him. That being the rival in front of him. 

"Just stay still, runt." He says this as he traces his finger at Blue's pelvis with such delicacy that it was rather surprising. His breathe hitches when he touches a certain spot of his, making him squirm and release more of those small whines and whimpers. "See? Yer startin' to like it, kid. I can make ya feel good, y'know. Just stop squirmin' around, yeah?" Fell's voice matches with his touch. Soft, gentle, but a hint of roughness in it. Blue wants to give in, but he knows that what he is trying to do him is wrong. He shakes his head frantically. This was an activity for only lovers to accomplish. It should never be forced onto one if they are not willing to. This was wrong, but he couldn't stop it-

"Don't act like ya got a choice." 

The touches suddenly become more violent, trying to stimulate Blue into forming his magic quicker. But he doesn't give in that easily. He thrashes under his duplicate's hold and moves away from the grabby, cold hands. He's flipped around before he could say anything, the left side of his face forced down onto the carpet. He tries yelling, but skeletal fingers are stuffed down his throat, resulting in strangled, choking sounds.

"I bet ya like it when they treat ya like this, eh? Acting tough and all, but really yer just a little slut." Blue groans, shutting his eye sockets tightly and wishing he would just disappear into thin air. But his thoughts are quickly replaced with immense pain as the skeleton straddling him begins to twist his arm at an awkward angle, making him wail into the fingers forced deep in his mouth. He thrashes like he did before, in hopes that this monster will let him go, but to no avail. "I said _**stop**_!" And he immediately does, though he can't stop the constant rattle of his bones.

"That's better." His twin speaks softly, but his fingers continue their vicious movements, and it's not long before magic begins to pool at the small pelvis. Blue can't believe himself anymore-

**_This can't be happening. This can't be happening. This can't be happening. This can't be happening-_ **

His magic. Fully forms. 

He wriggles again and again.

"Well, well, well. Look what we have here. Seems like somebody's a lil desperate, huh?" His harsh phalanges move roughly across the cyan blue magic, making the Sans on the floor to jerk and cry out in protest. "Don't worry, my lil Blueberry. I'll give ya what ya want. But, I got a question for ya...

"What has thirty teeth and holds back a monster?"

It was fear that ran in Blueberry when he heard the unzipping of the other's short, along with something hot poking at his somewhat sensitive magic, and he already knew what it was.

"My zipper."

He wanted to scream for help, wanted to cry out until his voice was hoarse and gone. He wanted his brother Papyrus to come and rescue him from this terrible nightmare. The once happy-go-lucky Sans released a distressed cry around the sharp phalanges, which only edged the taller skeleton even more. "Don't cry, my little Berry. It'll be over _real_ quick." And with that, he begins to push himself into his unwilling double.

Blue panics and instinctively bites down, harshly, into the bones invading his mouth. Quickly, the taller of the duo hisses and retreats his hands, blood trailing down Blue's chin, along with cyan drool. He looks at his hand and at Blue for a while, growling and shoving the small one's face deeper into the floor. 

"Y'know. I was bout to let ya have it nice n easy. But now ya really pulled the last straw-" He clenches and unclenches his injured hand, eyes glaring right through Blueberry's small skull.

"Yer gonna regret it." With the head of his member inside the quivering mess, he fully slams himself in sans(heh) hesitation. But the one under Fell cries out in displeasure and grips at the floor as if it were the only thing keeping him alive. It was too much for him. 

"That's what ya get for actin' up, kid." 

With that settled, he pulls out, only to slam back in twice as harsh as before. Blue whines unpleasantly, trying once more to get away from the imposter, but ends up with the same results. Fell sets himself at a steady pace, but it's in a savage and cruel way that forces out a grunt or whimper out of Blue with each thrust. "Look at how nice ya look like this. Such a slutty expression," he leans down, not stopping his actions, "I like ya-Ah-better like this than with that ridiculous smile of yers." A long lick is placed on Blue's tear-stricken face and he absolutely _hates_ it. He hates himself for letting this happen to him. He should've been strong enough to fight him off- But-

But now it's too late.

"P-Please- Have m-Ah! M-Mercy!" Blue's pleads helplessly to the other, but the other is too focused on the look of pure repugnance and unpleasantness on Blue that it is trancing to Fell. "God, ya look so good like this. I wonder how yer brother managed to hold himself from bending ya over and fucking ya up." 

His thoughts come to a jarring halt at the mention of Papyrus, and the twisting for his liberation acts up again. His brother- Where was he. He should have been here by now. To save him- Was he at Muffet's again? What if he's too inebriate to function again? Has Blue ever even crossed Papy's mind at all throughout the course of the day?

He continues to create various scenarios on why his older sibling was not present, but the constant jabs of his duplicate overwhelmed him. He cried out in pain, and only cried more when he thought about Papyrus finding him like this.

Fell took note of this.

"Bet ya like this, eh?"." He comments, leaving another long stripe of red saliva along his neck vertebrae, occasionally peppering a few bite marks here and there. "Now be a good kitten for me, will ya?" His voice is replaced with the sickly sweet tone, and it makes Blue shake in pure fear. He laughs a gruff laugh and sinks his sharpened fangs into Blue's weak, fragile bones. It earns him a very satisfying cry. "Gee kid. Yer getting me real close-" 

Another wave of panic washes over him. Fell stops for a bit, but shakes his head and quickens his pace. "I bet ya want me to cum, eh? I bet ya want me deep inside ya-" A few grunts follow after that.

"Well- Here ya g-go!" With a couple of more jabs into Blue's magic, he emits a satisfied groan as he pushes himself in to the hilt, spilling his scarlet seed deep into the tremulous Sans. He rides out his orgasm and after a while, pulls out, completely mesmerized by the sight before him. Blue lay on the floor, panting and drooling with a dazed and unfocused look in his eyelights as they constantly seemed to fade. He was still shaking and the little one tried to cover himself from Fell's hungry eyes, and Fell made no move to stop him. Red, glowing semen dripped from his abused entrance, but it was already beginning to disappear. At least Fell was satisfied.

For now.

He tugs his shorts back up and stands up to continue admiring Blue from above. He was still crying. "C'mon, kid. It wasn't _that_ bad, now was it?" He receives small snivels in response. **_Maybe he... shouldn't have- No._**

**_T_** **_he damage was already done._ **

"Hey." Blue looks up, wiping the remaining tears that stained his innocent face. "Ya mind if I stay here for a bit?" 

Did he just-

"Wh-...After you d-do this, you expect me t-to be calm about th-this!?" He was sobbing again. "Why did you d-do it!? That was only for LOVERS TO DO! WHAT IS W-WRONG WITH YOU?!?! YOU **M-MONSTER**!!" Fell was a bit taken back by this. He feels a ping of... something in his chest.

Love? Disgusting. Hate? No.....

**_Guilt?_ **

He thinks this over and shakes his head. "Just shut up."

"No!"

With a fist to the side of Blue's face, he instantly cries out, but says no more. Fell pulls him up by the collar of his shirt and growls. "I said. **Shut**. **Up**." Blue is more than willing to obey. He could taste the metallic substance in his mouth. "If you tell anyone about this," his eyes go dark for a moment, but come alight with a single shining red orb in his left eyesocket,

"You're gonna have a bad time."

He drops Blueberry and he groans as he lands on his coccyx, sending painful bolts up his spine. "Actually, why don't we tell your brother? Maybe he'll wanna join us next time, huh?"

"D-Don't bring Papyrus into this! He h-had nothing to do with this!"

Fell chuckles. "Gee, sorry, sweetheart. Yer really fond of him, eh? You wouldn't mind if I.. borrowed him for a bit, would ya?" He cackles at Blue's horrified expression. 

"Pl-Please don't hurt him.." 

**_He wouldn't dare._ **

**_"_** I can't promise you that, bucko." And just as he appeared, he teleports away before Blue has the chance to protest. He pulls his femurs up to his chest, stares at the wall for a while before breaking down and sobbing into the silence of his once safe home. He cried and cried until he could give out no more, until his voice had completely gone out. Hours after his alternate self had left, Papyrus still wasn't home. He called out into the stillness of the house, again and again. He called out Papyrus name over and over like a record stuck on replay. He wanted his brother, wanted those warm arms to rock him to sleep, wanted him to say it was all just a terrible dream. He called out once more,

_**But nobody came.** _

**Notes for the Chapter:**

> bitch what the fuck im shook

**Author's Note:**

> I'm going to Hell for this.


End file.
